Not Applicable
1. Field of Invention
This invention relates to the sampling of staple fibers from a batch thereof and subsequent preparation, conditioning and testing of the length and strength of the fibers in the sample. Improved length and strength data are needed for determining the performances and economic values of the fiber for processing into yarns and into knitted, woven and nonwoven fabrics or paper.
Staple fiber refers generally to non-continuous fibers whose maximum lengths range from less than one inch to several inches. Natural staple fibers include cotton, wool, flax, and other like fibers. Chopped rayon, nylon, polyester and other man-made fibers also fall into the classification of staple fibers. Also included among staple fibers are cellulose-based fibers employed in papermaking.
The economic values of staple fibers depend upon their length and strength characteristics, since these and other characteristics determine the technical performance characteristics and economic values of yarns and fabrics constructed therefrom. Length and strength characteristics include statistical properties which reflect the variations in the distributions of lengths and strengths found in bulk or batch samples of staple fibers. For natural fibers, these statistical variations can be very significant. It follows that the length or strength data products measured require careful attention to technical aspects of sampling, sample preparation, including conditioning, and measurement. Similarly, the economic consequences of the measurements and the full costs of said measurements must also be carefully considered.
For examples, in some applications the longest 2.5% of the fibers in the fiber length distribution are most important economically, in a positive sense. That is, longer fibers are more valuable, as they enable manufacture of stronger and more even yarns. For other applications the weight fraction of fibers less than 0.5 inch (so-called short fiber content) are most important economically, in a negative sense. That is, high SFC cotton can yield unacceptable yarns and fabrics. Similar considerations apply to strength data products. For both length and strength testing, improved measurements are needed, plus it is increasingly important that the measurements be done not only in special, expensive, conditioned laboratories by trained personnel but in general, unconditioned environments by unskilled personnel.
Staple fibers, and cotton fibers particularly, are commonly classed employing standards supported by many national and international governmental and non-profit organizations. The United States Department of Agriculture""s Agricultural Marketing System is the leading organization, world-wide, which employs prior art instruments, such as HVI=High Volume Instruments, to measure length and strength of cotton fibers. There are important economic consequences to these measurements. The International Textile Manufacturer""s Federation is another organization which evaluates and recommends fiber quality measurement systems for its members, primarily through its Working Groups on fiber quality measurements. Both USDA and ITMF have suggested that improved measurement technologies are needed to correct said measurement deficiencies in HVI and other prior art instruments and to correct certain aberrations in the marketing system. Accordingly, this invention, and inventions by some of the same inventors described in co-pending patent applications, seek to offer such improvements.
The focus of this application is improved measurement of Length and Strength. With regard to Length and Strength, prior art technologies are inherently deficient in representativeness of the fibers sampled and in precision and accuracy of the measurements, particularly in the areas of short fiber content and strength and elongation of fibers. Prior art methods are most particularly deficient in the areas of testing sample specimens which are properly equilibrated with respect to moisture content or, more accurately, equilibrated with respect to those data products which are sensitive to moisture content of the fibers. Further, such known apparatus and methods are themselves unnecessarily expensive and require relatively sophisticated test personnel and expensive, conditioned laboratories. Accordingly, the broadest objectives of our invention are to provide for less biased, more accurate and more precise measurements of Length and Strength on ultra rapidly conditioned specimens in an internal environment, such that the instrument can be cost-effectively operated in non-conditioned environments and by unskilled personnel.
2. Description of the Related Art
WO 01/20321, xe2x80x9cConditioning and Testing Cotton Fibersxe2x80x9d, published Mar. 22, 2001, the entire content of which is incorporated herein by reference, discloses, among other things, novel ultra rapid sample conditioning methods using combinations of water in aerosolized state (particles, with and without chemical additives) and gaseous state (molecules, but not necessarily steam). That pending application also discloses the need for careful attention to the preparation of samples of cotton fibers preparatory to and in the course of their being tested. In particular, it is also noted in that publication that the xe2x80x9chistoricalxe2x80x9d testing environment for cotton fibers of 65% relative humidity and 70 degrees F. (21 degrees C.) dry bulb temperature is of importance within the testing environment as opposed to the laboratory overall environment.
Numerous other patent and open literature references are relevant to this disclosure. U.S. Pat. No. 6,029,316 discloses methods and a machine for xe2x80x9crapidlyxe2x80x9d conditioning so-called xe2x80x9cClasser""s or HVI Samplesxe2x80x9d of cotton fiber prior to testing. U.S. Pat. No. 5,537,868 discloses conditioning the xe2x80x9cTesting Zonexe2x80x9d of fiber quality instruments with known air conditioning methods. U.S. Pat. No. 5,361,450 discloses conditioning internal xe2x80x9cProcessing Zonesxe2x80x9d of processing equipment, not testing instruments, and with known air conditioning means. U.S. Pat. Nos. 5,491,876 and 5,483,844 disclose needle sampling means for single fiber testing, not the tapered beard specimen disclosed herein. U.S. Pat. No. 3,057,019 discloses the well-known xe2x80x9cHertelxe2x80x9d sampler which is still used today. These patents are incorporated herein in their entirety by reference. Distinguishing features between them and the instant invention will be made at the appropriate points in this disclosure.
Sampling of staple fibers commonly involves withdrawing a xe2x80x9cbeardxe2x80x9d of fibers from a mass (batch) of the fibers. A xe2x80x9cbeardxe2x80x9d is formed when fibers from a batch of staple fibers are grasped by a needle or needles or by a clamp, then combed and brushed to straighten and parallelize the fibers. Several fiber length statistics can be derived from this beard. One such fiber length is the average length of the longer one-half of the fibers (upper half mean length) and is customarily reported in both 100ths and 32nds of an inch for cotton fibers. Another is Mean Length. another, Short Fiber Content, is provided.
Fiber strength is reported in terms of grams per tex, not in force per unit area, as for metals or other materials of construction. A tex unit is equal to the weight in grams of 1,000 meters of fiber. Therefore, the strength reported in the maximum force in grams required to break a bundle of fibers one tex unit in size. Strength measurements can be made on the same beards of fibers that are used for measuring fiber length.
Our measurements of length and strength only generally follow known art. The improvements disclosed herein relate primarily to internal, ultra rapid conditioning of the beards, to less-biased sampling effected by single needles and multiple, closely-spaced needles, to improved sensing of the beard""s length and strength characteristics, and to rotary motions of the sampling needles.
The present invention comprises a method and apparatus for the collection of samples of staple fibers from a quantity (batch) of such fibers without material consideration of the xe2x80x9cconditionxe2x80x9d of the fibers within the batch,(e.g., the relative humidity and/or temperature of the environment immediate the batch of fibers), and thereafter physically converting each sample of fibers to a tapered beard geometry. Each beard is grasped at one end thereof with the fibers thereof extending unsupported therefrom. The beard is conveyed to a location proximate the entrance to an air flow channel whereupon conditioned air flowing into the flow channel moves along, over and past the beard, causing the free ends of the fibers to enter the flow channel and become aligned generally along the length of the flow channel. Continued flow of conditioned air into and through the flow channel, hence in a direction generally parallel to the length of the fibers which make up the beard, ultra-rapidly conditions only the fibers of the beard. Air flow rates may reach hundreds or even thousands of ft/sec velocity within the flow channel and conditioning of the fibers may be accomplished within a matter of seconds.
In accordance with one aspect of the present invention, the flow of conditioned air from the flow channel, preferably is recycled to the source of conditioned air, which is located remote from the flow channel.
Within the flow channel, the strength of the fiber is tested. Thereupon, the beard is withdrawn from the flow channel and conveyed to a strength test station. In one embodiment, the flow of conditioned air is at least partially diverted toward a strength test station from which this conditioned air is captured and recycled to the source thereof. Notably, in the present invention, only that air which enters the flow channel and/or which may flow past the strength test station is conditioned, the environment associated with the fiber batch, the collection of a sample of fibers from the batch, the physical treatment of the collected sample of fibers to form a tapered beard of the fibers and substantially all locations other locations aside from the flow channel and proximate the strength test station of the apparatus is at ambient relative humidity and temperature.
In accordance with another aspect of the present invention, the physical collection of the samples from the batch of fibers includes a rotating carrier, such as a hollow cylinder having one or more collector needles mounted on the outer circumference thereof. This carrier is rotated about its longitudinal axis with such axis being oriented radially of a plurality of beard preparation stations and at least one test station whereby the collection, preparation and testing of the beard is effected at locations spaced about the circumference of the carrier. This arrangement provides for reversal of the direction of rotation of the carrier to effect selective extent of entry of the beard into the flow channel, withdrawal of the beard from the channel and conveyance thereof to a further test station, for example, and eventual reversal of the direction of rotation of the drum for removal of the beard from its collector so that the collector is cleaned of fibers in preparation for its subsequent movement through the batch of fibers and collection of a further sample of such fibers.